The Wooden Bricklayer

This post is the first in an occasional series that shows what goes on behind the scenes in my workshop.

So, wooden bricklaying?  Can that be right?

Yup, bricks made of wood, laid like a brick wall.  An unusual technique but very useful in the right place.  The main difference is that in the wood-working version there’s no thick line of cement between the bricks – indeed most wood glues need the gap between surfaces to be less than 0.1mm to reach full strength – so the joints need to be tight to work well and look good.

The brick-building technique can be used for many things but I’m using it now for a very specific purpose – to create large slender semi-circular “spines” for a fantastic commission I’m working on. The challenge is to create 2500mm long, semi-circular curves of solid wood, 80mm wide and only 40mm thick. And to make things more interesting, they need to be stable, strong and have a flawlessly smooth surface.  Here’s a snap of the finished curve.

Brick built semi-circle in solid Ash

A semi-circular “spine” made from bricks of solid Ash.

So how’s it done?  Imagine laying a brick wall, one layer then the next.  Of course we’ll need to offset the layers by half a brick so that the joins between adjacent bricks don’t ever line up with the joins in the layer below.  Now imagine doing that for a semi-circular wall.  Remember there’s no thick layer of cement here so we’ll need to cut the two ends of each brick to a specific angle, so that when they’re laid end-to-end the resulting wall follows a curve.  You’ll end up with something like the image below.  You can see the individual bricks forming the rough curve with its many sharp corners.  And I’ve drawn on, in dark blue, the smooth shape we’d eventually like to get out of all this.

The rough curve made from bricks

Here’s what a brick built rough curve would look like. The smooth curve we’d like to get out of this is shown in dark blue.

So having glued all this together, it’s just a matter of trimming off the sharp corners to leave the smooth curve.  On this scale that’s not a trivial job!  The curving faces must be utterly smooth, perfectly parallel to each other, consistently semi-circular, within 1mm of a defined radius and at exactly 90 degrees to the flat faces.  And I need to do that repeatedly to produce others of exactly the same shape and dimensions.  I won’t outline all the gory details but here’s a hint: imagine a giant set of compasses that would allow you to draw a semi-circle of that size.  Well, I designed and built something similar, but instead of a pencil at the end, marking the curve, there’s a spinning blade that cuts the curve.  It cuts away the sharp corners of the bricks, leaving only the smooth curve.  Job done.

Here’s a close up of the curve.  Look closely and you’ll see the bricks and the layers all jointed nice and tight.

Close-up of brick building

Close-up of brick building showing the bricks of solid ash, glued up and trimmed.